1. Field
The present disclosure relates generally to dopant implantation of a work piece and, more specifically, to smoothing a time-averaged ion implantation beam profile by subjecting the beam to a fluctuating magnetic field.
2. Related Art
Dopant implantation, such as ion implantation, is a process used in fabricating integrated semiconductor devices whereby conductivity-altering impurities, such as ions, are introduced into a work piece, such as a silicon wafer, a semiconductor plate, a glass plate, or the like. An ion implanter or ion implantation tool may include an ion source to generate the impurity material and a mass analyzer to form an ion implant beam with ions of a specific mass-to-charge ratio. Other components of an ion implanter may include accelerators, decelerators, magnetic field devices, electrical field devices, beam current measurement systems, and scan systems. Among these components, magnetic field devices (e.g., magnetic multipoles) may be integral for manipulating the beam to achieve a certain profile for required dose uniformity on the work piece. For example, a spot beam may require a beam profile shaped like a Gaussian curve (i.e., the concentration of ions may be highest in the center, and the ion concentration may fall off quickly as the distance from the center increases).
However, in the example of a spot beam, the desired Gaussian curve-shaped beam profile may not always be readily achievable due to the limitations of beam tuning, and specifically the difficulties of removing noise, spikes, peaks, shoulders, and the like from a beam profile (i.e., correcting ion beam portions with ion concentration that is too high or too low). In addition, obtaining the desired beam profile may come at the expense of sacrificing beam current or increasing beam tuning time, which may result in an overall decrease in productivity. Accordingly, smoothing an ion implantation beam profile is desired without sacrificing beam current and without sacrificing productivity from increased beam tuning time.